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OPERATION OF THE ABET-2201 POWER CONDITIONING UNIT
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OPERATION OF THE ABET-2201 POWER CONDITIONING UNIT

Ayhan A. Mutlu, Ph.D., and Mahmud Rahman, Ph.D.
Department of Electrical Engineering, Santa Clara University
500 El Camino Real, Santa Clara, CA 95053



December 12, 2004





















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1. Introduction



With the advent of electricity and technological breakthroughs, electrical energy has been made
available at a reasonable cost through an elaborate and efficient distribution grid system to
households and businesses alike operating various kinds of appliances that run on electricity.
The local distributors of electrical energy charges the consumers based on the consumers rate of
electrical energy consumption called power expressed in numbers of thousands of watts, i.e.,
kilowatts (kW). The electrical quantity kW that represents the rate of energy consumed can be
minimized if the circuitry is optimized in a way that there is less spurious energy lost. The
ABET 2201 product, if incorporated into the electrical circuit, is able to achieve such
minimization. In addition, the ABET-2201 brings about a number of other benefits to the
consumer without introducing any adverse effects, or "side effects." A good understanding of
various aspects of how electrical power is consumed in a circuit is therefore essential to
understand how this product works. The principle of operation of the ABET-2201, based on
theoretical concepts which are substantiated by measurement evidences, is presented in the
following.


2. Types of loads and their electrical behavior

Theoretically, there are three basic types of loads in an electrical system, e.g., resistive,
inductive, and capacitive. While electrical energy is expended in pure resistive loads, electrical
energy is not expended but stored in ideally inductive and capacitive loads. Although all
practical loads and appliances at a consumers site incorporate these three types of ideal loads, it
is appropriate to categorize them as mostly resistive, inductive or capacitive. The following is an
example of common practical loads that are used in a household.

a.

Resistive: Oven, light bulbs, iron, electric heaters, etc.
b.

Inductive: Appliances with motors and transformers are examples of inductive loads
which include air-conditioners, washers, dryers, refrigerators, induction motor, power
transformer, lighting ballasts, welder or induction furnace, etc.
c.

Capacitive: Rechargeable batteries, etc.

Since the currents flowing in inductive and capacitive loads are half a cycle out of phase, it is
possible to make their sum zero at any particular time by adjusting their magnitudes,
consequently reducing the total current magnitude flowing through the Energy-meter (kW-hour
meter) installed by the local distributors to monitor energy consumed by a subscriber. This is the
essence of "power factor correction," where power factor refers to cosine of the phase angle
between the voltage and the total current. The phase angle = t, where t = time and = 2/T is
the angular frequency of power supply and T = 1/f, where the principle frequency f of the power
being delivered is usually 60 Hz. For purely resistive load, = 0
o
, hence power factor for
resistive load = cosine 0
o
= 1. For purely inductive and capacitive loads, power factor = cosine
(±90
o
) = 0. Power factor correction implies to the situation where the inductive load current is
balanced by capacitive load current thus reducing the total current to a minimum and the phase
angle between the voltage and the total current representing the algebraic sum of the individual
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load currents approaches 0
o
, i.e., cosine 0
o
= 1. At lower power factor, the total current is larger
and vice versa.

The current passing through the current coil of the Energy-meter installed by the power
distributor to monitor power consumption is the algebraic aggregate of the individual resistive,
inductive, and capacitive currents flowing in different loads of the household. Power distributors
require the industrial consumers to keep the power factor of the household read at the Energy-
meter above say, 0.8, since power factors below 0.8 would require the distributors supply larger
currents, therefore running larger generators which in turn would cost them more. Also, smaller
current associated with higher power factor will minimize various resistive losses in the
distribution system. Therefore, industrial consumers are charged a penalty at a predetermined
rate based on their operating power factor.

The ABET-2201 is capable of correcting the power factor toward various benefits of the
consumer as explained below.


3. The Role of the Capacitor in the Electrical Power System

Capacitor is a device that stores energy in the electric field established between a pair of
conductors on which equal but opposite electric charges have been induced. Historically,
capacitors have taken the form of a pair of thin metal plates, whether flat or tightly coiled up in a
cylinder (like a sushi roll), but every multi-conductor geometry exhibits the phenomenon of
capacitance.

The capacitance of a traditional flat-plate capacitor--and, resultantly, the amount of energy that
can be stored in the capacitor--is proportional to the surface area of the conducting plate and
inversely proportional to the distance between the plates. It is also proportional to the
permittivity of the dielectric substance that separates the plates, whether vacuum, air, or
specially engineered materials chosen for their high electrical permittivity.

In a direct-current (DC) circuit, a capacitor acts like an open circuit: no current flows through it,
though the potential difference initially induced between its conductors can serve as an
exponentially decaying energy source for the circuit. In an alternating-current (AC) circuit, a
capacitor cyclically stores and releases energy at twice the frequency of the forcing source.


3.1. Power Factor Correction

ABET-2201 brings the advantages of the power factor correction capacitor to household use.
Figure 1 shows a typical connection of the ABET unit in a household. This unit is usually
connected to the fuse panel where the electricity is distributed to different locations in the house.


As mentioned above, the current passing through the current coil of the Energy-meter installed
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by the power distributor to monitor power consumption is the algebraic aggregate of the
individual resistive, inductive, and capacitive currents flowing in different loads of the
household, as shown in Fig. 1. Since the currents flowing in inductive and capacitive loads are
half a cycle out of phase, it is possible to make their sum zero at any particular time by adjusting
their magnitudes, consequently reducing the total current magnitude flowing through the Energy-
meter.




Fig. 1. An example ABET-2201 installation in a typical household.

Figure 2 (a) illustrates the instantaneous supply voltage, and currents in resistive, inductive,
capacitive loads. It can be clearly seen that while the current in the resistive load is in phase with
the supply voltage (
= 0
o
), the current through the inductive load lags the supply voltage by a
quarter of a cycle (
= -90
o
), and the current through the capacitive load leads the supply voltage
by a quarter of a cycle (
= +90
o
). Figure 2 (b) displays the instantaneous supply voltage and the
total current with and without the ABET-2201 capacitive load. Figure 3 is an exploded view of a
section of Fig. 2 (b) showing clearly the reduction of the phase angle between the supply voltage
and the total current when ABET-2201 is connected to the system, thus improving the power
factor and consequently, reducing the total current magnitude. Due to the reduction in the total
current, the power loss (I
2total
x R
1
) in the resistance R
1
, between the wattmeter and the ABET-
2201, which varies from house to house, is also reduced. This is the instantaneous power saving
that is achieved by installing the ABET-2201. It is important to note that i) the resistance R
1
will
depend on the locations of the Energy-meter and ABET-2201, and ii) the power saving is
proportional to the square of the reduction in the current brought about by the ABET-2201.
Figure 4 presents average voltage, current, power, and power factor measured over a period of
one hour in an actual household. It is clearly observed that the power consumption is reduced
along w